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Hello Gents!

I'm working on a Mig-Ye8 - which progresses a bit slowly - and during test flights I run into some FM and visual issue I'm not sure with what data modification I can solve.

few of the symptoms:

- Autorotation during take of at around 154km/h, it already wants to raise nose up even when still bellow take off speed.

- during flight canard and stabilizator are not in a "straight" position (see top pic in level flight), not sure which of the followings I have to change. Did some up and down changes but no visual difference so far. CL0,CLa,CD0,CDL,Cmq,Cmad,Cyb,Clp or Cnb parameter. Stabs use the standard TW mig21 stab data, canards set somewhat similar to the f31 canard (due to position and size similarities) Although this angle problem not exists on the ground (see second pic) during high speed run or taxi.

 

This is the canards data: (Most of the data is wild guess to start out from something, so do not look for accuracy.)

 

[LeftCanard]

ParentComponentName=Nose

ModelNodeName=Canard_L

DestroyedNodeName=

ShowFromCockpit=TRUE

DetachWhenDestroyed=TRUE

DamageRating=DISABLED

MassFraction=0.005

HasAeroCoefficients=TRUE

LiftSurface=TRUE

CL0=-0.0198

CLa=0.1450

CD0=0.0006

CDL=0.0002

Cmq=-2.1048

Cmad=-1.1198

Cyb=-0.0087

Clp=-0.0061

Cnb=0.0042

CL0MachTableNumData=9

CL0MachTableDeltaX=0.40

CL0MachTableStartX=0.00

CL0MachTableData=0.972,0.984,1.000,0.763,0.534,0.387,0.205,0.169,0.086

CLaMachTableNumData=9

CLaMachTableDeltaX=0.40

CLaMachTableStartX=0.00

CLaMachTableData=0.934,0.979,1.000,1.070,1.208,1.983,1.588,1.284,0.976

CD0MachTableNumData=9

CD0MachTableDeltaX=0.40

CD0MachTableStartX=0.00

CD0MachTableData=1.494,1.120,1.000,0.962,1.343,1.601,1.371,1.288,1.226

CDLAlphaTableNumData=15

CDLAlphaTableDeltaX=4.00

CDLAlphaTableStartX=-28.00

CDLAlphaTableData=31.000,25.000,20.000,13.000,9.000,4.400,1.200,0.070,1.000,3.800,7.200,16.000,21.000,29.000,37.000

CmqMachTableNumData=9

CmqMachTableDeltaX=0.40

CmqMachTableStartX=0.00

CmqMachTableData=0.972,1.000,1.042,1.108,1.196,1.112,0.896,0.708,0.642

ClpAlphaTableNumData=15

ClpAlphaTableDeltaX=4.00

ClpAlphaTableStartX=-28.00

ClpAlphaTableData=1.474,1.361,1.264,1.182,1.121,1.068,1.034,1.012,1.000,1.015,1.034,1.079,1.134,1.208,1.285

XacMachTableNumData=9

XacMachTableDeltaX=0.40

XacMachTableStartX=0.00

XacMachTableData=-4.849,-4.852,-4.858,-4.876,-4.921,-5.024,-5.084,-5.136,-5.184

CheckStall=TRUE

CLmax=0.2977

AlphaStall=43.87

AlphaMax=48.64

AlphaDepart=54.41

StallLiftTableNumData=30

StallLiftTableDeltaX=10.00

StallLiftTableStartX=-180.00

StallLiftTableData=0.000,-0.014,-0.026,-0.044,-0.059,-0.049,-0.034,-0.015,0.000,0.021,0.054,0.107,0.152,0.220,0.266,0.370,0.577,0.882,0.494,0.288,0.182,0.096,0.041,0.000,-0.015,-0.034,-0.051,-0.028,-0.014,0.000

StallDragTableNumData=30

StallDragTableDeltaX=10.00

StallDragTableStartX=-180.00

StallDragTableData=0.001,0.012,0.043,0.082,0.152,0.221,0.294,0.408,0.564,0.795,0.937,1.018,1.142,1.122,1.000,1.122,1.142,1.018,0.937,0.749,0.562,0.451,0.367,0.292,0.201,0.123,0.062,0.026,0.008,0.001

StallXacShiftTableNumData=30

StallXacShiftTableDeltaX=10.00

StallXacShiftTableStartX=-180.00

StallXacShiftTableData=-0.324,-0.322,-0.275,-0.248,-0.235,-0.219,-0.202,-0.178,-0.161,-0.144,-0.120,-0.103,-0.087,-0.077,-0.074,-0.047,0.000,0.000,0.000,-0.047,-0.081,-0.103,-0.132,-0.168,-0.202,-0.224,-0.245,-0.275,-0.322,-0.324

DownwashAlphaTableNumData=30

DownwashAlphaTableDeltaX=10.00

DownwashAlphaTableStartX=-180.00

DownwashAlphaTableData=0.000,0.000,0.000,0.000,0.000,0.000,0.000,-0.004,-1.642,-3.229,-4.715,-6.050,-7.210,-8.151,-8.844,-4.737,0.831,6.428,9.837,8.241,5.677,3.883,1.961,0.000,0.000,0.000,0.000,0.000,0.000,0.000

Chord=1.18

Ymac=-0.94

MovingSurface=TRUE

ControlSystemID=1

MinExtentPosition=-1.36,4.718,0.043

MaxExtentPosition=-0.485,6.096,0.15

CollisionPoint[001]=-0.537,5.279,0.091

HasVortexEmitter=TRUE

VortexEmitterName=WingtipVortexEmitter

VortexPosition=-1.3,4.77,0.09

VortexG=3.5

SystemName[001]=LeftElevator

 

[RightCanard]

ParentComponentName=Nose

ModelNodeName=Canard_R

DestroyedNodeName=

ShowFromCockpit=TRUE

DetachWhenDestroyed=TRUE

DamageRating=DISABLED

MassFraction=0.005

HasAeroCoefficients=TRUE

LiftSurface=TRUE

CL0=-0.0198

CLa=0.1450

CD0=0.0006

CDL=0.0002

Cmq=-2.1048

Cmad=-1.1198

Cyb=-0.0087

Clp=-0.0061

Cnb=0.0042

CL0MachTableNumData=9

CL0MachTableDeltaX=0.40

CL0MachTableStartX=0.00

CL0MachTableData=0.972,0.984,1.000,0.763,0.534,0.387,0.205,0.169,0.086

CLaMachTableNumData=9

CLaMachTableDeltaX=0.40

CLaMachTableStartX=0.00

CLaMachTableData=0.934,0.979,1.000,1.070,1.208,1.983,1.588,1.284,0.976

CD0MachTableNumData=9

CD0MachTableDeltaX=0.40

CD0MachTableStartX=0.00

CD0MachTableData=1.494,1.120,1.000,0.962,1.343,1.601,1.371,1.288,1.226

CDLAlphaTableNumData=15

CDLAlphaTableDeltaX=4.00

CDLAlphaTableStartX=-28.00

CDLAlphaTableData=31.000,25.000,20.000,13.000,9.000,4.400,1.200,0.070,1.000,3.800,7.200,16.000,21.000,29.000,37.000

CmqMachTableNumData=9

CmqMachTableDeltaX=0.40

CmqMachTableStartX=0.00

CmqMachTableData=0.972,1.000,1.042,1.108,1.196,1.112,0.896,0.708,0.642

ClpAlphaTableNumData=15

ClpAlphaTableDeltaX=4.00

ClpAlphaTableStartX=-28.00

ClpAlphaTableData=1.474,1.361,1.264,1.182,1.121,1.068,1.034,1.012,1.000,1.015,1.034,1.079,1.134,1.208,1.285

XacMachTableNumData=9

XacMachTableDeltaX=0.40

XacMachTableStartX=0.00

XacMachTableData=-4.849,-4.852,-4.858,-4.876,-4.921,-5.024,-5.084,-5.136,-5.184

CheckStall=TRUE

CLmax=0.2977

AlphaStall=43.87

AlphaMax=48.64

AlphaDepart=54.41

StallLiftTableNumData=30

StallLiftTableDeltaX=10.00

StallLiftTableStartX=-180.00

StallLiftTableData=0.000,-0.014,-0.026,-0.044,-0.059,-0.049,-0.034,-0.015,0.000,0.021,0.054,0.107,0.152,0.220,0.266,0.370,0.577,0.882,0.494,0.288,0.182,0.096,0.041,0.000,-0.015,-0.034,-0.051,-0.028,-0.014,0.000

StallDragTableNumData=30

StallDragTableDeltaX=10.00

StallDragTableStartX=-180.00

StallDragTableData=0.001,0.012,0.043,0.082,0.152,0.221,0.294,0.408,0.564,0.795,0.937,1.018,1.142,1.122,1.000,1.122,1.142,1.018,0.937,0.749,0.562,0.451,0.367,0.292,0.201,0.123,0.062,0.026,0.008,0.001

StallXacShiftTableNumData=30

StallXacShiftTableDeltaX=10.00

StallXacShiftTableStartX=-180.00

StallXacShiftTableData=-0.324,-0.322,-0.275,-0.248,-0.235,-0.219,-0.202,-0.178,-0.161,-0.144,-0.120,-0.103,-0.087,-0.077,-0.074,-0.047,0.000,0.000,0.000,-0.047,-0.081,-0.103,-0.132,-0.168,-0.202,-0.224,-0.245,-0.275,-0.322,-0.324

DownwashAlphaTableNumData=30

DownwashAlphaTableDeltaX=10.00

DownwashAlphaTableStartX=-180.00

DownwashAlphaTableData=0.000,0.000,0.000,0.000,0.000,0.000,0.000,-0.004,-1.642,-3.229,-4.715,-6.050,-7.210,-8.151,-8.844,-4.737,0.831,6.428,9.837,8.241,5.677,3.883,1.961,0.000,0.000,0.000,0.000,0.000,0.000,0.000

Chord=1.18

Ymac=0.94

MovingSurface=TRUE

ControlSystemID=1

StructuralFactor=1.5

MinExtentPosition=0.486,4.718,0.043

MaxExtentPosition=1.36,6.096,0.15

CollisionPoint[001]=0.537,5.279,0.091

HasVortexEmitter=TRUE

VortexEmitterName=WingtipVortexEmitter

VortexPosition=1.3,4.77,0.09

VortexG=3.5

SystemName[001]=RightElevator

 

 

Also anyone has info that this bird had a second airbreak like the fishbed front of the ventral fin? I can't find any info or photo which says it had.

 

Thank you any info and advice in advance.

post-30564-0-37212600-1359613822_thumb.jpg

post-30564-0-06672900-1359613880_thumb.jpg

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You might start with "fixing" the Canard location. I do notice that you tell the Canards that they are located back at the stabilizer area versus ahead of the Cockpit: "XacMachTableData=-4.849,-4.852,-4.858,-4.876,-4.921,-5.024,-5.084,-5.136,-5.184"

 

Anything AHEAD of the CG is positive, behind the CG is negative.

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Panama red is correct. The Xmac table should start 1/4-1/3 of the way back from the leading edge of the surface, and terminate 1/2-2/3 of the distance back from the leading edge, which in the case of a canard, should be foreward of the model's center. Also, the Xmac tables should be applied at the mean chord of a given surface.

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Thank you very much PanamaRed and Fubar512 the info, honestly I had no clue about the meaning of +/- values in those parts. Just to make sure I understand it right we talk about the grey masked area on the pic bellow. (a bit slow on grasping after my 4th 12 hour shift this week)

 

Also I did a quick data change and correction, the good news it is now reverted in direction, so some fine tuning will still needed, the bad (at least for me) I will have to rewrite and change many things in the FM as now want to drop like a brick.

Is there any other related parameter which has this +/- relation? Also points should be given from root side outward the tip of the canard or from tip inward to root?

 

Thank you again! :drinks:

post-30564-0-92319400-1359700981.jpg

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Canards provide postive lift, not the slight static (CL0) downforce that elevators and horizontal stabs do (you are using horizontal stab values for your canards). Change this value CL0=-0.0198 to CL0=0.0198 on both canards

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Thank you Fubar512, the CL0 change solved the dropping. More fiddle and test will be after work.

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I might need a little more help. :blush: I did calculate the new CLa(DW), Mac, ymac values using Fubar512's tutorial from 2k7 with the aeroconverter and would like to go further with all the other drag,alpha,etc calculations as simply changing Tk's data with my actual data, resulted in a "nose into ground" attitude above 130km/h.

Is there a comprehensive guide about all related formulas or site which is preferable to use? Or should I buy a book about aerospace engineering?

An other question would be if I want to give lets say 21 reference values, what determines the sequence or parameters those values should be originated or their intervals. I mean is it speed (mach value in 0,1 steps) or altitude (1000m steps), or weight (kg), or ........ :dntknw:

Thank you in advance.

 

note btw: With the exception of XB70, kfir and J10 all canard (rafale, tyhoon, viggen, gripen, F31, F29) planes use negative Xacmach position values even when the min/max extend is only positive in Y-axis for the given mesh.

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Then the planes you listed have incorrect values. If you add a lift surface forward of the model's centerline, it should positive positional values.

 

As I often work 16-hour days, I cannot get back to my notes and test models until Friday evening at the earliest. When I do, I will post the canard values that I'm using for the as yet unreleased Su-33. But keep in mind that in the Sea Flanker's case those are movable surfaces, whereas (if I recall correctly) the Ye-8's canards were fixed, like the Mirages and the Kfir.

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Based on the data I read actually the canards were movable and locked above 1Mach due to unsolved controlling issues, but could be fix locked from the start too or any time if there were some complications. In the FM I use about 1,25M for lock-out speed.

Tanks for the info and kindness for your offer, do not worry I can't get to it before friday evening either.

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Here you go, Logan:

 

 

[LeftCanard]
ParentComponentName=Fuselage
ModelNodeName=canard_left
DestroyedNodeName=
ShowFromCockpit=TRUE
DetachWhenDestroyed=TRUE
DamageRating=DISABLED
MassFraction=0.007
HasAeroCoefficients=TRUE
LiftSurface=TRUE
CLa=0.043
CD0=0.0004
CDL=0.0012
Cmq=-0.7825
Cmad=-0.2818
Clp=-0.0025
Cnb=0.0055
CLaMachTableNumData=5
CLaMachTableDeltaX=0.40
CLaMachTableStartX=0.00
CLaMachTableData=1.001,1.000,0.979,0.910,0.938
CD0MachTableNumData=5
CD0MachTableDeltaX=0.40
CD0MachTableStartX=0.00
CD0MachTableData=1.825,1.000,1.028,2.494,2.773
CmqMachTableNumData=27
CmqMachTableDeltaX=0.10
CmqMachTableStartX=0.00
CmqMachTableData=0.868,0.872,0.897,0.937,1.000,1.095,1.240,1.475,1.904,2.935,7.322,-0.000,-0.000,0.246,1.152,0.121,0.494,0.568,0.599,0.609,0.598,0.591,0.578,0.558,0.529,0.495,0.464
ClpAlphaTableNumData=15
ClpAlphaTableDeltaX=4.00
ClpAlphaTableStartX=-28.00
ClpAlphaTableData=1.474,1.361,1.264,1.182,1.115,1.063,1.027,1.006,1.000,1.009,1.034,1.074,1.129,1.200,1.285
XacMachTableNumData=5
XacMachTableDeltaX=0.40
XacMachTableStartX=0.00
XacMachTableData=3.856,3.664,3.185,2.976,2.836
Chord=1.03
Ymac=0.983
MovingSurface=TRUE
ControlSystemID=1
StructuralFactor=1.00
MinExtentPosition=  -1.2907,1.6681,0.600
MaxExtentPosition=  -0.8907, 1.1481,0.600
SystemName[001]=LeftCan
HasVortexEmitter=TRUE
VortexEmitterName=F16LexEmitter
VortexPosition=-3.0007,1.1381,0.6000
VortexG=6.5
VortexUseNodeOffset=TRUE

[RightCanard]
ParentComponentName=Fuselage
ModelNodeName=canard_right
DestroyedNodeName=
ShowFromCockpit=TRUE
DetachWhenDestroyed=TRUE
MassFraction=0.007
HasAeroCoefficients=TRUE
LiftSurface=TRUE
CLa=0.043
CD0=0.0004
CDL=0.0012
Cmq=-0.7825
Cmad=-0.2818
Clp=-0.0025
Cnb=0.0055
CLaMachTableNumData=5
CLaMachTableDeltaX=0.40
CLaMachTableStartX=0.00
CLaMachTableData=1.001,1.000,0.979,0.910,0.938
CD0MachTableNumData=5
CD0MachTableDeltaX=0.40
CD0MachTableStartX=0.00
CD0MachTableData=1.825,1.000,1.028,2.494,2.773
CmqMachTableNumData=27
CmqMachTableDeltaX=0.10
CmqMachTableStartX=0.00
CmqMachTableData=0.868,0.872,0.897,0.937,1.000,1.095,1.240,1.475,1.904,2.935,7.322,-0.000,-0.000,0.246,1.152,0.121,0.494,0.568,0.599,0.609,0.598,0.591,0.578,0.558,0.529,0.495,0.464
ClpAlphaTableNumData=15
ClpAlphaTableDeltaX=4.00
ClpAlphaTableStartX=-28.00
ClpAlphaTableData=1.474,1.361,1.264,1.182,1.115,1.063,1.027,1.006,1.000,1.009,1.034,1.074,1.129,1.200,1.285
XacMachTableNumData=5
XacMachTableDeltaX=0.40
XacMachTableStartX=0.00
XacMachTableData=3.856,3.664,3.185,2.976,2.836
Chord=1.03
Ymac=0.983
MovingSurface=TRUE
ControlSystemID=1
StructuralFactor=1.00
MinExtentPosition=  1.2907,1.6681,0.600
MaxExtentPosition=  0.8907, 1.1481,0.600
SystemName[001]=RightCan
HasVortexEmitter=TRUE
VortexEmitterName=F16LexEmitter
VortexPosition=3.0007,1.1381,0.6000
VortexG=6.5
VortexUseNodeOffset=TRUE

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Thank you very much Fubar512!

Based on the first comparison I seem to try give a lot more of the various "things", many which might not belong to this object properties. Like CdL tables, drag and stall values etc. Also if I make my calculated Cla (not the one above shown from me) to it's 1/10th value than the flips and autoroll stops. Actually the plane takes an auto roll above 214km/h (but keeps an 4,5deg attitude which I set for the AI for take off roll) and if throttle is given than auto rises to the air at around 324km/h. The stab and canard positions during flight seem to straightened out.

It was a great help. Now I going to fiddle around some of the values.

 

 

@Blackbird: Thank you. To be honest this is my second take on it also, and since last summer hardly had time to do much on it, but slowly going to make it complete. Recently only the FM got "worked" on it and if time allows it than going to make some parts mapping also tomorrow.

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Auto roll? Sounds as if you given both sides the same Ymac coordinates. Left is always a negative value (ie, Ymac=-0.935), while the right surface is always postive.

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Your models looks very good, nice attention to details! Im a big fan of prototypes ,specialy the soviet ones. We have enough western targets around, for our new toys! Expect another MiG Prototypes this summer too from my end ;)

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Auto roll? Sounds as if you given both sides the same Ymac coordinates. Left is always a negative value (ie, Ymac=-0.935), while the right surface is always postive.

Sorry my "miss-labeling" about autoroll I meant when the plane lifts it's nose up automatically due to sufficient lift characteristics on certain parts. Probably there is a better term for it (autorotate?), it doesn't meant the roll condition during flight.

 

 

@blackbird: yes we do have little to beat the blueforce with. I planed 4 versions for this bird which might be its evolutionary road given the time - no 2seater though.

I do have an other one in the works. Found a drawing in one of the aviation books about the mig29 when there was very little to know about, but probably it is just a hypothetical drawing.

post-30564-0-71709900-1360463824_thumb.jpg

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